1. Technical Field of the Invention
The present invention relates generally to control apparatus for electric generators and electric power generation systems.
More particularly, the invention relates to a control apparatus for an automotive alternator, which can reliably inform a reset thereof to an engine control unit (ECU), and an automotive power generation system that includes such a control apparatus.
2. Description of the Related Art
A conventional power generation system for a motor vehicle, such as the one disclosed in U.S. Pat. No. 5,767,636, includes an automotive alternator, a voltage regulator for regulating the output voltage of the alternator, and an ECU that communicates with the voltage regulator for controlling power generation of the alternator. More specifically, the ECU sends to the voltage regulator a command signal that represents command values for power generation control parameters; the voltage regulator regulates the output voltage of the alternator according to the command signal. With such a configuration, it is possible to suitably control the power generation of the alternator according to the operating condition of the engine.
Moreover, the alternator is generally installed in an engine compartment and supplies electric power to both a battery and electric loads via a charge line. The alternator also supplies power to the voltage regulator which is generally built in the alternator.
Furthermore, the voltage regulator may be falsely reset due to various noises imposed on the power lines of the power generation system. For example, on the power lines, ignition noises may be imposed in the case of the engine being a gasoline engine; power noises may be imposed when the alternator drives an inductive load, such as a motor; great voltage ripples may be imposed when the power generation system operates without the battery.
When the voltage regulator is reset, all the command values for the power generation control parameters having been sent from the ECU to the voltage regulator are initialized. However, since the ECU cannot be aware of the initialization of those command values, it continues its control on the power generation of the alternator on the assumption that those command values are still effective in the voltage regulator. As a result, malfunctions will be caused in performing a stabilization control of the output voltage of the alternator, a fuel economy-improving control, or a stabilization control of idle rotation. Furthermore, when the command values for the power generation control parameters are incorrectly initialized in the reset of the voltage regulator caused by the noises, the voltage regulator can no longer suitably control the alternator; however, the ECU cannot be aware of such a wrong condition of the voltage regulator.